WARSAW, FEB. 1 -- Dissident activists in Poland, Hungary, Czechoslovakia and the Soviet Union staged demonstrations and issued statements today protesting repression in Romania in an unprecedented instance of coordination among Warsaw Pact opposition movements.

In Warsaw and Budapest, hundreds of persons gathered outside the Romanian embassies in mid-day rallies, while in Prague, about 60 people carried out a 24-hour hunger strike. Activists in all three capitals switched off lights in their apartments in a symbolic protest of the drastic economic austerity suffered by Romanians.

The protest actions were supported in a statement by Soviet human rights activist Andrei Sakharov that was endorsed by four other Soviet dissidents, Lev Timofeyev, Sergei Kovalyov, Raisa Gogaroz and Naum Meiman. The East European groups also issued statements, and Polish activists unsuccessfully attempted to deliver a petition to Romanian Embassy officials.

"We know . . . the enormous price you must pay for fighting for the right to human dignity and the right to live free of hunger and terror," said a statement addressed to Romanians and signed by 49 Polish activists, including leaders of the banned Solidarity trade union. "We believe deeply that our shared dream for a free and democratic central Europe will be fulfilled."

The various activities, which led to the arrest of more than a dozen protesters in Warsaw, marked the first time that East Bloc dissidents in several countries have organized simultaneous demonstrations and underlined the growing links among the region's independent political movements.

During the last 18 months, organizations in Eastern Europe promoting human rights, disarmament, democratic opposition to communist rule and even environmental protection have begun contacting one another and organizing activities ranging from multinational declarations and petitions to independent peace conferences and clandestine strategy sessions along international borders.

The initiatives have been facilitated in part by the climate of increased political tolerance in Hungary and Poland as well as by greater opportunities for international telephoning and travel in most Warsaw Pact countries. Contacts for events such as today's protest have been routed through foundations and exile groups in Western Europe, which translate and distribute documents and relay messages.

Key organizers of the joint actions say the development of the Soviet leadership of Mikhail Gorbachev has given Eastern European activists more common goals to pursue even as it has lessened the risks of repression.

"For the first time there is the chance of a region-wide movement for reform rather than a process in just one country like Czechoslovakia in 1968 and Poland in 1980," said Miklos Haraszti, a leading Hungarian activist, in an interview last year.

While dissident groups in Poland, Czechoslovakia and Hungary have maintained loose contacts for a number of years, the communication gained new momentum in late 1986. In October, a statement on the 30th anniversary of the Hungarian revolution was drawn up and signed by more than 125 persons from five Warsaw Pact countries, including 54 Hungarians, 28 Poles, 24 Czechoslovaks, 16 East Germans and several Romanians.

One month later, a large number of East European and Soviet activists joined West European and U.S. peace and human rights workers in signing a special memorandum to the Conference on Security and Cooperation in Europe on "giving real life to the Helsinki accords," the 1975 agreement sealing the detente process between East and West and containing a number of joint commitments on human rights.

Since then, the East Europeans have worked on several other joint statements and independent peace activists have managed to gather for two independent conferences in the last year, one in Warsaw and one in Budapest.

Today's demonstrations were prompted by an appeal last month by Charter 77, which acted following reports of rioting by workers in the Romanian city of Brasov in November. The rebellion was one of the most serious shows of protest by Romanians against the neo-Stalinist regime of President Nicolae Ceausescu, which in recent years has imposed austerity on the country while maintaining the East Bloc's most repressive security apparatus.

Only in Poland did government security forces attempt to halt the demonstrations. Militia and secret police quickly seized demonstrators when they sought to lift banners calling for "human rights for Romanians and Solidarity." Among those detained were Warsaw Solidarity chief Zbigniew Bujak and Jan Jozef Lipski, head of the illegal Polish Socialist Party.